From Citizendium, the Citizens' Compendium
Octonions are a non-commutative and non-associative extension of the real numbers. They were were first discovered by John Graves, a friend of Sir William Rowan Hamilton who first described the related quaternions. Although Hamilton offered to publicize Graves discovery, it took Arthur Cayley to rediscover and publish in 1845, for this reason octonions are also known as Cayley Numbers.
Definition & basic operations
The octonions, , are a eight-dimensional normed division algebra over the real numbers.